JP2008244390A - Vapor growth system and vapor growth method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a vapor growth system and a vapor growth method which can improve the uniformity of a temperature distribution in the plane of a heated wafer and can evenly generate a crystal film. <P>SOLUTION: The vapor growth system includes a chamber 101, a holder 104 having a susceptor 103 on which a wafer 102 stored in the chamber 101 is placed, an inner heater 105 and an outer heater 106 which are provided in the holder 104 to heat the wafer 102 from the backside, airpipes 107 which faces the inner heater 105 and inject cooling gas, and a temperature measuring part 108 which is provided outside the chamber 101 to measure the surface temperature of the wafer 102. Thus it is possible to locate the singular point of a temperature in an error portion of a temperature distribution on the wafer 102. Further, it is possible to improve the uniformity of the temperature distribution in the plane of the wafer 102 by locally cooling the singular point of the temperature. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a vapor phase growth apparatus and a vapor phase growth method, and in particular, by obtaining a uniform in-plane temperature distribution over the entire surface of a silicon wafer heated in the epitaxial growth apparatus, the uniformity of the film thickness of the produced epitaxial growth film is improved. It relates to means for improving.

In the manufacture of semiconductor devices such as ultra-high speed bipolar and ultra-high speed CMOS, single crystal epitaxial growth technology with controlled impurity concentration and film thickness is indispensable for improving the performance of semiconductor devices.
In general, an atmospheric pressure chemical vapor deposition method is used for epitaxial growth for forming a single crystal thin film on a wafer, and a low pressure chemical vapor deposition (LPCVD) method is used in some cases. The wafer is accommodated in the chamber, and the silicon source and boron compound are heated and rotated while the chamber is maintained at normal pressure (0.1 Mpa (760 Torr)) or in a vacuum atmosphere of a predetermined degree of vacuum. A process gas mixed with a dopant such as a phosphorus compound or an arsenic compound is supplied. Then, a thermal decomposition reaction of a process gas or a hydrogen reduction reaction is performed on the surface of the heated wafer to produce a crystal film doped with boron (B), phosphorus (P), or arsenic (As). .

  Further, the epitaxial growth technique is required to produce a high-quality crystal film uniformly and thickly in order to manufacture a high-performance semiconductor element such as an IGBT (Insulated Gate Bipolar Transistor). For example, in a simple MOS device or the like, only a film thickness of several μm or less is required, whereas in an IGBT or the like, a film thickness of several μm to several tens of μm is required. Therefore, by rotating the wafer at a high speed, a new gas is sequentially brought into contact to increase the growth rate of the crystal film, and the in-plane uniformity of the film thickness generated by uniformly heating the wafer is increased. Yes.

  FIG. 7 is a conceptual diagram showing a vapor phase growth apparatus provided with a plurality of heaters for uniformly heating the wafer, and FIG. 8 is based on temperature information measured by the temperature measuring unit 308 for the in-heater 305 and the out-heater 306. It is a conceptual diagram which shows a mode that the wafer 302 is heated, controlling it. When the wafer 302 is heated using both the in-heater 305 and the out-heater 306 of this apparatus, the central portion of the wafer 302 is heated by receiving radiant heat from the in-heater 305. The outer edge of the wafer 302 is heated by being applied to the wafer 302 as conduction heat through the susceptor 303 heated by the out heater 306. Then, under the influence of both radiant heat from the in-heater 305 and conduction heat from the out-heater 306 via the susceptor 303, a portion having a higher temperature than the central portion or outer edge portion of the wafer 302 is generated in the surface of the wafer 302. (Temperature singularity). As a result, an error is caused in the film thickness of the crystal film generated around the singular point of the temperature of the wafer 302.

Conventionally, when performing a vapor phase growth reaction, the wafer 302 is placed in a state where the outer edge of the wafer 302 and the susceptor 303 are in contact with each other. As a result, heat is conducted from the outer edge portion of the wafer 302 to the susceptor 303 so that it can easily escape. In response to this, a plurality of heaters are provided to supplementarily heat the outer edge portion of the wafer 302, thereby suppressing a temperature drop at the outer edge portion of the wafer 302. However, this in turn has caused a state in which a further temperature error is caused in other portions of the wafer 302 surface.
For this reason, even if an error in the temperature distribution in the wafer 302 surface is corrected by controlling the output of either or the entire heater, an error in the temperature distribution is eventually generated in another part.
As a result, the temperature distribution cannot be made uniform over the entire surface of the wafer 302, and the film thickness of the crystal film to be produced cannot be made uniform.
Further, if an error occurs in the temperature distribution in the wafer 302 during the vapor phase growth reaction, crystal defects are generated in the generated crystal film, which can be used to manufacture a high-performance semiconductor element. Quality wafers cannot be produced (see Patent Document 1).

Therefore, the temperature distribution error generated in the surface of the wafer 302 must be eliminated by locally adjusting the temperature of the in-heater 305 or the out-heater 306 rather than adjusting the temperature of the wafer 302 by controlling the output of the heater. This problem cannot be overcome.
JP 2001-345271 A

  As described above, in the conventional vapor phase growth apparatus, the temperature distribution in the wafer surface cannot be made sufficiently uniform due to the structure, and the uniformity of the film thickness of the crystal film formed on the wafer surface can be improved. could not.

  The present invention overcomes such problems, improves the uniformity of the temperature distribution in the heated wafer surface, and can improve the uniformity of the film thickness of the crystal film formed on the wafer surface, and A vapor deposition method is provided.

The vapor phase growth apparatus of the present invention is
A chamber;
A holder housed in a chamber and having a susceptor for mounting a wafer;
A heater provided in the holder for heating the wafer placed on the susceptor;
An air supply pipe that is provided facing the heater and injects a cooling gas toward the heater;
A temperature measurement unit that is provided outside the chamber and measures the temperature of the surface of the wafer;
It is characterized by providing.

  It is preferable that the air supply pipe is provided to face a portion of the heater overheating the wafer.

  It is preferable that a plurality of air supply tubes are provided at substantially equal intervals so as to be positioned on the rotation circumference of the wafer.

  It is preferable that the air supply pipe injects a cooling gas whose flow rate is controlled based on the surface temperature of the wafer measured by the temperature measuring unit.

The vapor phase growth method of the present invention comprises:
A vapor phase growth method in which a wafer is placed on a susceptor of a holder accommodated in a chamber, a process gas is supplied to the wafer, and the wafer is heated by a heater provided in the holder to perform a vapor phase growth reaction. Because
The surface temperature of the wafer is measured using a temperature measuring unit, and the temperature of the wafer is controlled by injecting a cooling gas to the heater so that the surface temperature of the wafer becomes uniform at a predetermined temperature.

  According to the present invention, the portion of the heater overheating the wafer can be locally cooled, and the uniformity of the in-plane temperature distribution can be improved. Therefore, the thickness distribution of the crystal film to be generated can be made uniform.

In addition, if a new heater is provided separately to control the temperature of the wafer, a new singular point of temperature is newly generated in the wafer surface, which makes it more difficult to make the temperature in the wafer surface uniform. . Therefore, the fundamental problem for obtaining a uniform temperature distribution in a wafer undergoing vapor phase growth reaction cannot be solved.
In addition, controlling the surface temperature by locally cooling the heater and eliminating the overheated part of the wafer is implemented and introduced compared to methods that control the wafer temperature by providing a new heater. Easy to do is also part of the usefulness.

  As described above, by using the present invention, it is possible to provide a vapor phase growth apparatus and a vapor phase growth method that can manufacture a wafer having a highly uniform film thickness distribution of a crystal film generated on the wafer.

(Embodiment 1)
First, the first embodiment will be described in detail based on the drawings.
A vapor phase growth apparatus 100 in FIG. 1 is provided with a chamber 101, a holder 104 having a susceptor 103 on which a wafer 102 accommodated in the chamber 101 is placed, and the wafer 102 heated from the back surface. An in-heater 105 and an out-heater 106, an air supply pipe 107 for injecting a cooling gas provided facing the in-heater 105, and a temperature measuring unit 108 for measuring the surface temperature of the wafer 102 provided outside the chamber 101. Is provided.
Here, among the members necessary for generating the crystal film on the surface of the wafer 102, the components other than those necessary for explaining the first embodiment are omitted. Further, the scales and the like of the members shown in FIG. Hereinafter, the same applies to each drawing.

  The wafer 102 is placed in a recess formed in a circular plate-like susceptor 103 provided on the upper portion of the holder 104. A penetrating opening is formed at the center of the recess, and is arranged so as to be able to directly receive radiant heat from the in-heater 105 and the out-heater 106 provided in the holder 104. The in-heater 105 is a heat source formed in a predetermined substantially circular outline provided with a slit so as to form a conductive path in a circular resistor material plate. The in-heater 105 heats the central portion of the wafer 102. The outheater 106 is a heat source formed in a ring shape by providing slits in the same circular resistor material plate so as to form conductive paths. The outheater 106 heats the outer edge of the wafer 102 together with the susceptor 103. As a result, it is possible to assist the heating of the outer edge portion of the wafer 102 where heat easily escapes because it is in contact with the susceptor 103, and to suppress the temperature drop.

  However, in the temperature control method as described above, a range in which both the radiant heat from the in-heater 105 and the out-heater 106 and the conduction heat from the susceptor 103 are received occurs in the wafer 102 surface. In the range of 5 mm to 20 mm from the outer edge portion of the wafer 102, a point (temperature singularity) in which the temperature becomes too high compared to other portions has occurred. For this reason, the predetermined range centered on the singular point of this temperature is overheated compared to other portions of the wafer 102, causing an error in the temperature distribution in the wafer 102 plane.

In order to overcome this and improve the uniformity of the temperature distribution in the surface of the wafer 102, in the first embodiment, the wafer 102 is indirectly cooled by providing a mechanism for locally cooling the in-heater 105.
2 is a perspective view of the holder 104 in a state where the wafer 102 is not placed on the susceptor 103 and a partially cutaway perspective view showing the internal structure of the holder 104. FIG. 3 is a bottom view of the holder 104 shown in FIG. It is the conceptual diagram which showed the part from upper direction.
As shown in FIG. 2, the rotating drum 110 below the holder 104 is connected to a rotating mechanism (not shown) provided outside the chamber 101 and can be rotated. Then, as shown in FIG. 3, 90 ° on the same circumference of the horizontal cross section of the rotating drum 110 so that the air supply pipe 107 passing through the inside of the rotating drum 110 injects the cooling gas so as to face the in-heater 105. They are arranged at equal intervals. Thus, the cooling gas is injected from the air supply pipe 107 so that the four points of the in-heater 105 that heats the rotation circumference of the wafer 102 are locally cooled.

The wafer 102 rotates as the holder 104 rotates. For this reason, when the four equally spaced points of the in-heater 105 that are directly below the rotation circumference of the wafer 102 are cooled, the portions on the rotation circumference of the wafer 102 are equally cooled. That is, the position where the air supply pipes 107 are arranged is not limited with respect to the position in the circumferential direction of the wafer 102, and the interval between the air supply pipes 107 is set so that the portions facing the rotation circumference of the wafer 102 are evenly cooled. It is sufficient if they are equally provided.
In the first embodiment, four air supply pipes 107 are provided. However, the number of air supply pipes 107 is not limited to this, and a cooling gas can be jetted to the in-heater 105 so that the wafer 102 can be sufficiently cooled to a predetermined temperature. If it is in a state. Further, the material of the air supply pipe 107 may be any material that does not have the possibility of affecting the inside of the chamber 101 such as metal contamination or particle contamination, such as quartz or silicon carbide (SiC).

FIG. 4 shows how the in-heater 105 and the out-heater 106 heat the wafer 102 and the error of the temperature distribution at the singular point of the temperature generated on the wafer 102. The portion of the in-heater 105 that hits the rotation circumference of the wafer 102 is locally shown. It is the conceptual diagram which showed a mode that the wafer 102 was cooled indirectly by cooling.
The air supply tube 107 disposed so that the tip is located 5 mm to 30 mm below the lower surface of the inheater 105 cools the portion of the inheater 105 that is heating on the rotation circumference of the singular point of the temperature of the wafer 102. Cooling gas is blown out.
Here, the cooling gas injected from the air supply tube 107 may be any gas that does not disturb the environment of the vapor phase growth reaction in the chamber 101, such as room temperature hydrogen (H ₂ ). The cooling gas flow rate is 100 SCCM (Standard
Cubic Centimeter per Minutes) 1.69 × 10 ⁻¹ Pam ³ / S-5SLM (Standard
Liter per Minutes) 8.45 Pam ³ / S is preferred.
In such a state, a cooling gas having a predetermined flow rate is injected and cooled to a predetermined position of the in-heater 105 to locally suppress heating due to radiant heat from the in-heater 105 with respect to a temperature singular point generated in the wafer 102. .
As a result, by injecting the cooling gas, the wafer 102 can be cooled indirectly and locally, and the uniformity of the temperature distribution in the wafer 102 surface can be improved.

Here, since the in-heater 105 heats the wafer 102 to 1100 ° C. or higher, the in-heater 105 itself is in a state of generating heat up to about 1400 ° C. to 1500 ° C. Therefore, since the amount of heat generated by the inner heater 105 itself even when cooled by direct injection at normal temperature H ₂ or the like is large, not the temperature is abruptly changed as inner heater 105 is damaged by thermal stress. Therefore, there is no need to provide a special temperature adjusting mechanism in the cooling gas supply unit, and it may be supplied at room temperature.

A window 109 is provided on the upper surface of the chamber 101 so that the inside of the chamber 101 can be seen. A temperature measurement unit 108 is provided so as to face the surface of the wafer 102 through the window 109, and measures the temperature of the surface of the wafer 102. The temperature measurement unit 108 has a plurality of radiation thermometers, and is controlled to measure the surface temperature of the wafer 102 in conjunction with each other. In the first embodiment, three radiation thermometers are provided.
Here, the radiation thermometer 118 is arranged so as to measure the temperature of the central portion of the wafer 102 heated by the radiant heat from the in-heater 105. Then, the output of the in-heater 105 is controlled based on the measured temperature information, and the temperature of the central portion of the wafer 102 is adjusted.
Further, the radiation thermometer 128 is arranged so as to measure the temperature of the outer edge portion of the wafer 102 which is a portion heated by the radiant heat from the outheater 106 and the conduction heat from the heated susceptor 103. Then, the output of the outheater 106 is controlled based on the measured temperature information, and the temperature of the outer edge portion of the wafer 102 is adjusted.
The radiation thermometer 138 is arranged so as to measure the temperature of a singular point of the temperature in the wafer 102 plane.
Here, in order to specify the position where the temperature singularity occurs in the wafer 102 surface, a thermal analysis of the relationship between the wafer 102 and the in-heater 105 and the out-heater 106 is performed in advance. And the radiation thermometer 138 is arrange | positioned in the position which can capture the temperature fluctuation of the singular point of the temperature specified from this result.
Based on the temperature information measured as described above, a cooling gas controlled at a predetermined flow rate is injected from the air supply pipe 107 to the in-heater 105 so that the temperature distribution in the wafer 102 surface is uniform.
Thus, the in-heater 105 that is heating the overheated portion of the wafer 102 can be cooled to a predetermined temperature, and the wafer 102 can be indirectly cooled. As a result, the temperature distribution error centered on the singular point of the temperature generated in the wafer 102 can be eliminated.

As described above, by performing temperature control at three points in the surface of the wafer 102, a uniform temperature distribution can be obtained from the center portion to the outer edge portion of the wafer 102.
Then, a process gas containing a raw material component for generating a crystal film is supplied to the wafer 102 in such a state. Then, a thermal decomposition reaction or a hydrogen reduction reaction is performed on the surface of the wafer 102, so that a crystal film having a uniformly controlled film thickness can be generated.
As a result, if the vapor phase growth apparatus and the vapor phase growth method in the present embodiment are used, the film thickness required for manufacturing a high-performance semiconductor element can be uniformly controlled, and there is no crystal defect. Quality wafers can be manufactured.

The process gas supplied in this embodiment is, for example, any one of monosilane (SiH ₄ ), dichlorosilane (SiH ₂ Cl ₂ ), trichlorosilane (SiHCl ₃ ), etc., which are silicon film forming gases, and a carrier gas. It formed by adding a predetermined dopant gas to a mixed gas of H ₂ as a.
As the dopant gas, boron-based diborane (B ₂ H ₆ ), phosphorus-based phosphine (PH ₃ ), or the like is used. When diborane is added, a p-type crystal film can be formed, and when phosphine is added, a n-type crystal film can be formed.

(Embodiment 2)
Next, Embodiment 2 will be described in detail based on the drawings.
FIG. 5 shows an air pipe 207 that can move a portion to be cooled of the in-heater 205 when the position of the singular point of the temperature generated in the wafer 202 changes due to the environment of the vapor phase growth reaction or the change of members. 1 is a conceptual diagram showing a phase growth apparatus 200. FIG.

The singularity of the temperature generated on the wafer 202 depends on various conditions such as the balance between radiant heat and conduction heat due to the difference in distance between the wafer 202 and the in-heater 205 and out-heater 206, and the difference in heat capacity due to the size and thickness of the susceptor 203. The position where this occurs also varies.
In the present embodiment, the vapor phase growth in which the temperature measuring unit 208 grasps the position of the temperature singularity under any condition and can move the position of the air supply pipe 207 in accordance with this to eject the cooling gas. The apparatus will be described.

A temperature measurement unit 208 measures the surface temperature of the wafer 202 through a window 209 provided on the upper surface of the chamber 201. At this time, the radiation thermometer 218 measures the temperature of the central portion of the wafer 202 heated by the in-heater 205, and the radiation thermometer 228 is heated by the radiation heat of the in-heater 205 and the out-heater 206 and the conduction heat from the susceptor 203. The temperature of the outer edge of the wafer 202 is measured. Based on the measured temperature information, the outputs of the in-heater 205 and the out-heater 206 are controlled.
The radiation thermometer 238 measures the temperature of the wafer 202 while moving in a radial direction a predetermined distance between a portion measured by the radiation thermometer 218 and a portion measured by the radiation thermometer 228 in the wafer 202 plane. .
By acquiring three pieces of temperature information of the wafer 202 measured by the radiation thermometers 218, 228, 238, the temperature distribution in the radial direction within the wafer 202 surface can be grasped. As a result, it is possible to detect a portion where a singular point of temperature occurs in the surface of the wafer 202, and it is possible to capture a change in the position of the singular point of temperature generated in the surface of the wafer 202.

Then, the air supply pipe 207 is moved to a position where the cooling gas is ejected to the portion of the in-heater 205 that heats the singular point of the temperature of the wafer 202.
In such a state, the in-heater 205 is cooled by ejecting a cooling gas having a predetermined flow rate from the air supply pipe 207 so that the temperature distribution in the surface of the wafer 202 becomes uniform.
As a result, the wafer 202 can be indirectly cooled by cooling the in-heater 205.

FIG. 6 shows that in the holder 204, the air supply pipe 207 can move a predetermined distance with respect to the radial direction of the wafer 202, for example, from directly below the outer edge portion shown at 207a to directly below the central portion shown at 207b. It is a conceptual diagram which shows a mode.
When the temperature measuring unit 208 captures the temperature singularity in the wafer 202 plane, the four air supply pipes 207 are moved equidistantly in synchronism with the position of the in-heater 205 that heats the temperature singularity. It arrange | positions so that the position of the in-heater 205 which hits a rotation circumference may be cooled.
Thereby, the temperature error at the singular point of the temperature generated in the wafer 202 can be eliminated, and a uniform in-plane temperature distribution can be obtained.

  Here, the process gas is supplied to the wafer 202 in such a state to generate a crystal film, the holder 204 is rotated by a rotation mechanism (not shown), and the wafer 202 is rotated accompanying the rotation, etc. The description overlapping with the content described based on 4 is omitted.

  The embodiment has been described above with reference to specific examples. The present invention is not limited to the above-described embodiments, and can be variously modified and implemented without departing from the scope of the invention.

For example, in the second embodiment, by providing the movable radiation thermometer 238, the position can be supplemented even when the temperature singularity fluctuates. However, instead of the temperature measurement unit 208 having a plurality of radiation thermometers as described above, a radiation thermometer that scans with a predetermined width in the radial direction of the wafer can also be used.
With this method, the temperature distribution in the radial direction of the wafer can be grasped only by arranging one radiation thermometer. If the temperature distribution in the radial direction of the wafer is grasped, the temperature measurement for controlling the output of the in-heater and the out-heater and the temperature measurement for capturing the singular point of the temperature on the wafer can be performed simultaneously. it can.

Furthermore, in the second embodiment, the same rotation circumference of the wafer can be cooled by synchronizing the movement of the movable air supply tube. For example, among the plurality of air supply tubes, a position symmetrical to the center point of the holder 204 is used. The two points provided in the wafer can be made to respond to each other and moved in synchronization, so that two points in the radial direction of the wafer can be cooled uniformly.
As a result, even when a plurality of temperature singularities are generated on the wafer, the temperature error can be corrected by moving the air supply tube sequentially to obtain a more uniform temperature distribution within the wafer surface.

  In the present invention, the epitaxial growth apparatus has been described as an example of the vapor phase growth apparatus. However, the present invention is not limited to this, and any apparatus for generating a predetermined crystal film on the wafer surface may be used. For example, an apparatus for the purpose of growing a polysilicon film may be used.

  In addition, although description of parts that are not directly required for the present invention, such as the configuration of the apparatus and the control method, is omitted, the required apparatus configuration, control method, and the like can be appropriately selected and used.

  In addition, all the vapor phase growth apparatuses that include the elements of the present invention and can be appropriately modified by those skilled in the art, and the shapes of the respective members are included in the scope of the present invention.

It is a conceptual diagram shown in order to demonstrate the structure of the vapor phase growth apparatus in Embodiment 1 of this invention. It is the partially broken perspective view shown in order to demonstrate the structure inside the holder in Embodiment 1 of this invention. It is a conceptual diagram which shows the bottom face part of the holder in Embodiment 1 of this invention from upper direction. It is a conceptual diagram which shows a mode that a heater heats the wafer in Embodiment 1 of this invention, and a mode that the cooling gas ejected from an air supply pipe cools a heater. It is a conceptual diagram shown in order to demonstrate the structure of the vapor phase growth apparatus in Embodiment 2 of this invention. It is a conceptual diagram which shows the bottom face part of the holder in Embodiment 2 of this invention, and a movable air supply pipe | tube from upper direction. It is a conceptual diagram shown in order to demonstrate the structure of the conventional vapor phase growth apparatus. It is a conceptual diagram which shows a mode that the specific point of temperature arises on a wafer in the conventional vapor phase growth apparatus.

Explanation of symbols

100, 200 ... Vapor growth apparatus 101, 201 ... Chamber 102, 202 ... Wafer 103, 203 ... Susceptor 104, 204 ... Holder 105, 205 ... Inheater 106, 206 ... Outheater 107, 207 ... Air supply pipe 108, 208 ... Temperature Measuring unit 109 ... Window 110 ... Rotating drum 118, 128, 138, 218, 228, 238 ... Radiation thermometer

Claims (5)

A chamber;
A holder housed in the chamber and having a susceptor on which a wafer is placed;
A heater provided in the holder for heating a wafer placed on the susceptor;
An air supply pipe that is provided facing the heater and injects a cooling gas toward the heater;
A temperature measuring unit that is provided outside the chamber and measures the temperature of the surface of the wafer;
A vapor phase growth apparatus comprising:   2. The vapor phase growth apparatus according to claim 1, wherein the air supply pipe is provided to face a portion of the heater overheating the wafer.   3. The vapor phase growth apparatus according to claim 1, wherein a plurality of the air supply tubes are provided at substantially equal intervals so as to be positioned on a rotation circumference of the wafer.   4. The air supply pipe according to claim 1, wherein the air supply pipe injects a cooling gas whose flow rate is controlled based on a surface temperature of the wafer measured by the temperature measurement unit. The vapor phase growth apparatus according to item. Vapor phase growth in which a wafer is placed on a susceptor of a holder accommodated in a chamber, a process gas is supplied to the wafer, and the wafer is heated by a heater provided in the holder to perform a vapor phase growth reaction. A method,
The surface temperature of the wafer is measured using a temperature measuring unit, and the temperature of the wafer is controlled by injecting a cooling gas to the heater so that the surface temperature of the wafer becomes uniform at a predetermined temperature. Vapor phase growth method.

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